Extraction of oxygenated compounds



S .8m Qmv SSY E QES n N M l T 4 2 Sheets-Sheet 1 INVENTORSI- IS 0n HMM AJ@ W5 .fr Td 5@ A A HARBAN I'AL EXTRACTION OF OXYGENATED COMPOUNDS .wSQQQQ mwS RSSB 3 sept, 19, 195o- Flled Sept 30 1949 Sept. 19, 1950 A. A. HARBAN ErAl.

mmcnon oF oxYcENATEn conpomms 2 Sheets-Sheet 2 Filed sept. so. 1949 @qui Ok wvsm n 7W L n mmm mmh Wm m .0 r AJ .4 r UE w MH@ r .Afavw Patented Sept. 19, 1950 EXTRACTION OF OXYGENATED COMPOUNDS Arthur A. Harhan, Hammond, and Carl E. Johnson, Griiith, Ind., assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application September 30, `1949, Serial No. 118,746

15 Claims.

'Ihis invention relates to the extraction of oxygenated compounds from mixtures thereof with aliphatic hydrocarbons. More particularly, this invention relates to processes for the selective extraction of oxygenated organic compounds, particularly neutral oxygenated organic compounds, from oils comprising aliphatic hydrocarbons by the employment of certain amine salts of sulfonic acids as selective extraction solvents.

We have discovered that certain amine sulfonates lare surprisingly effective selective solvents for neutral, oxygenated organic compounds, as well as aromatic hydrocarbons and sulfur compounds, in admixture with aliphatic hydrocarbons, e. g., certain natural or synthetic hydrocarbon oil fractions. We havev further found that said amine sulfonates can be prepared relatively cheaply, have relatively low toxicity, and have relatively mild corrosive properties, which permits their employment in conventional equipment. The amine sulfonate solvents employed in the process of the present invention are characterized by surprisingly low or negligible solubility thereof in the raffinate phase produced by the extraction process, are readily recoverable, and have physical properties which enable them to be employed as selective extraction solvents for various oxygenated compounds at readily attainable temperatures and pressures. Moreover, said amine sulfonates are characterized by surprisingly great thermal stability, which permits their use in high temperature extraction processes such as extractive distillation processes.

It is an object of this invention to provide a process for the selective extraction of neutral, oxygenated organic compounds from their mix' tures with aliphatic hydrocarbons, including both acyclic and alicyclic hydrocarbons which may be completely saturated or may contain one olenic unsaturation per molecule. Another object of this invention is to provide a process for the selective extraction of one or more neutral, Oxygenated, oil-soluble organic compounds, such as alcohols, ethers, aldehydes, ketones, esters, lactones, acetals and the like having at least 4 carl bon atoms in the molecule, from their solutions in hydrocarbon oils, such as the solutions produced by the catalytic reduction of carbon monoxide (HCS or Hydrocarbon Synthesis process),

solutions produced by the modied HCS process known as the Synol process, solutionsproduced by the exidation of various :aliphatic hydrocarbon fractions, or from hydrocarbon fractions derived from shale oils. Another object of this invention is to provide the art of selective extracf.

and from the appended figures.

The novel solvents employed in the selective extraction process of this invention are amine sulfonates having the general formula:

wherein R1 and R2 are selected from the class consisting of hydrogen and saturated hydrocarbon radicals, R3 is a saturated hydrocarbon radical, and R4 is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals.

Thus, the saturated hydrocarbon radicals may be alkyl radicals, cycloalkyl radicals, cycloalkylalkyl and aralkyl radicals. The amine sudfonate solvents of this invention contain between 4 and 20 carbon atoms, inclusive, per molecule.

Examples, given by way of illustration and not necessarily for limitative purposes, of suitable alkyl radicals are: methyl, ethyl, n-propyl, isopropyl, n-butyl, amyl, octyl, nonyl, hexadecyl and octadecyl.

Illustrative examples of suitable cycloalkyl radicals include cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, ethylcyclopentyl, endomethylene-cyclohexyl (bicyclo[2,2,1]heptyl) and 2- methyl-bicyclo [2,2,1lheptyl.

Examples of suitable cycloalkyl-alkyl radicals include cyclohexylmethyl, cyclohexylethyl, cyclopentylpropyl, and the like.

Examples of suitable aralkyl radicals in the above general formula include benzyl, 2-phenylethyl, Z-phenylpropyl, w-xylyl, naphthomethyl and the like.

R4 may be an alkyl, cycloalkyl, cycloalkyl-alkyl, aralkyl, aryl, alkaryl or cycloalkyl-aryl radical.

Examples of suitable R4 aryl radicals include phenyl, naphthyl and derivatives -containing nuclearly-substituted chlorine atoms, etc.

TABLE I Amine Radical Aem Dit Radical o C Tricthylamine- 35 Do -43 Mono-n-butylamine. A-60 'lri-n-butylamine 40-60 Iriethylamine -48 l\lono-nbutylaminc 30-00 We have found that equal volumes of the salts of Table I and the following solvents are miscible at 20-25 C.: methanol, 95% ethanol, acetone and benzene, and that the salts are insoluble in hexane.

We have discovered that certain triethylamine sulfonates are particularly desirable for the purposes of the present invention because they are relatively non-viscous, non-volatile liquids at normal temperatures, exhibit high selectivity for neutral, oxygenated organic compounds, aromatic hydrocarbons and sulfur compounds, and are characterized by relatively little change in viscosity with temperature. Certain properties of triethylamine salts of the lower alkanesulfonic acids which are particularly desirable for employment in the claimed process are set forth in Tables II and III.

l Period of eiilux in seconds from Saybolt Universal vlscosimetcr.

TABLE III Eect of added water on the viscosity of triethylamine (C1-C4) alkanesulfonates H2O H2O H10 H2O Vis. at 100 F., SSU 274. 4 245. 0 174.9 71.5 Vis. at 130 F., SSU 143.1 128.3 100. 2 51.6 Vis. at 210 F.. SSU 55.1 52.8 47. 7 35. 5 Viscosity Index 126 126. 5 133. 5 21. 8 Pour Point, F. -55 -50 -50 -65 The amine sulfonates dened by the above general formula are either normally liquid or relatively low melting solids and may be used for the purposes of the present invention without auxiliary solvents or diluents. However, because of their solubility in water, methanol, ethanol, etc., it may be desirable to employ the amine sulfonate solvents of the present invention together with more or less of such diluents or co-so1vents,vto modify the selectively of the amine sulfonates. lower their melting point, or for other reasons. The amount of auxiliary solvents employed can be selected with reference to specic cases. Ordinarily, only between about l and about 20 weight per cent based on the amine sulfonate will be employed. If desired, the amine sulfonates may be employed together with between about 1 and about 20 per cent of sulfonic acid, preferably the sulfonic acid that is combined in the amine sulfonate.

In the process of the present invention the selective solvent is employed as a liquid, melt or solution; the feed stock may be charger to the process as a liquid, solution or vapor. The present invention, therefore, relates to liquid-liquid or liquid-vapor extraction processes employing the above defined amine sulfonate solvents. When the feed stock is charged to the process as a Vapor, the process is one of extractive distillation.

By the term extraction, as employed in the appended claims, it is intended to include not only liquid-liquid extraction processes, but also extractive distillation processes employing the above defined solvents. It is well appreciated that these processes differ somewhat from each other in efliciency or applicability in specific instances, but they are actually and theoretically related (note, for example, H. J. Hibshman, 1nd. Eng. Chem. 4l, 1366 (1949)).

In general, the extraction operations of the present invention are conducted at temperatures between about 20" C. and about 180 C., the particular extraction temperature depending upon the specific amine sulfonate solvent, the melting point of the solvent, whether or not it is used alone or with an auxiliary solvent or diluent, the degree and selectivity of extraction sought t0 Ibe effected, etc.

The volume of selective solvent employed depends, among4 other things, upon the neutral, oxygenated organic compound content of the feed stock, the temperature of operation, and desired eciency, but will generally fall within a range of about 0.1 to about 10 volumes of amine sulfonate per volume of charging stock. In liquid-liquid extraction, sucient pressure is maintained upon the system to keep the feed stock in the liquid phase. Usually, pressures within the range of about 0 to 100 p. s. i. g. are sufficient for this purpose, it -being appreciated that the particular pressure necessary in a given case can be determined readily. When the feed stock is to be employed in the vapor phase, suitable pressures at which the feed stock will be a vapor at the extraction temperature can be determined readily.

Certain hydrocarbon oil fractions derived from petroleum, coal, shale, etc., are known to contain neutral, oxygenated organic compounds. It is desired in numerous instances to remove these compounds in order to produce rened hydrocarbon oils. ing range of gasoline, naphtha, kerosene, gas oil, heater oil, or lubricating oil stocks. The process of the present invention is particularly-applicable to the rening of gasoline boiling range hydrocarbon oils containing neutral, oxygenated organic compounds, and to such oils containing a. substantial proportion of mono-oleflnic hydrocarbons, as in the case of synthetic gasoline or Such oils may boil within the boil-f naphtha boiling range fractions derived from the Hydrocarbon Synthesis (HCS) process, especially when alkalized iron catalysts are employed in said process.

In the HCS process, carbon monoxide is reduced by hydrogen to produce a variety of gaseous, liquid and solid hydrocanbons in the presence of eighth group metal catalysts, particularly iron, cobalt and nickel catalysts. The synthetic gas, consisting essentially of a mixture of carbon monoxide and hydrogen, is produced by partial oxidation of natural gas or other hydrocarbon gas, suitable operating conditions being, for example, a temperature of about 2500 F. and a pressure of about 250 p. s. i. g. Synthesis gas may also Ibe produced by conventional processes of reforming natural gas with steam in the presence of a catalyst; when desired, both the oxidation and reforming processes may be employed to generate synthesis gas. The Il'2:CO ratio in the synthesis gas may be adjusted as desired, usually to a ratio between about 2:1 and about 5:1 in the reactor. A variety of iron-containing catalysts may be employed. The catalysts may be prepared by the reduction of fused iron oxides, mill scale, or pyrites-ash, and may be sintered before or after reduction to obtain improved activity and life. The iron catalysts are suitably promoted by small amounts of alkali metal components such as KOH, KzC, KF or the corresponding sodium compounds. A suitable catalyst, for example, is the commercial ammonia synthesis catalyst frequently employed in the United States, known as the C. C. C. catalyst; essentially this catalyst is iron promoted by small amounts of alkali. Synthesis can be effected in reactors utilizing a iluidized iron catalyst bed at temperatures between about 450 and about 700 F. and pressures between about 200 and about 500 p. s. i. g.

Among the hydrocarbon products produced in the above-described synthesis operation are olenic hydrocarbon fractions which contain paraiiin hydrocarbons of approximately the same carbon number and boiling range and, in addition, a substantial amount of preferentially oilsoluble, neutral oxygen-containing organic compounds such as aldehydes, ketones, esters, lactones, acetals, ethers, alcohols, and the like, having at least 4 carbon atoms in the molecule. The oxygenated compounds present in the abovementioned HCS olen hydrocarbon fractions cannot be removed to any satisfactory degree by simple washing with water, alkalies, or specific group reagents, for example, aqueous sodium bisulte for the removal of carbonyl compounds.

The proportion, and possibly to some extent the nature of the oxygenated compounds produced in the iron-catalyzed HCS process, will naturally depend upon and vary with the specific catalyst, catalyst age and operating conditions employed.

The oleilnic hydrocarbon content of the normally liquid HCS olefin fractions often ranges between about 50 and about 75 percent by weight and the concentration of oxy compounds ranges from about 5 to about 30 weight percent.

A range of representative compositions of alkali washed HCS fractions, obtained by the treatment of water gas with an alkalized iron catalyst at a temperature of about 60G-660 F. and a `pressure of about 250 p. s. i. g. in a fiuidized bed reactor employing a space velocity of 5 standard cubic feet per hour of CO in fresh feed per pound of iron is shown in Figure 1.

In typical operations with an alkalized iron catalyst derived by reduction of pyrites, oxygenated compounds were found to total between 5 and 8 percent by weight of the oil stream and to comprise about 65% of carbonyl compounds, 30% of alcohols and 5% of carboxylic acids, mostly in the Css-C12 range. The C6-7-8 alcohols and carbonyl compounds were present in largest quantities. v

'I'he selective extraction process of the present invention is not limited in its application to HCS product fractions containing neutral, oxygenated organic compounds. Thus, the process of the present invention may be applied to products derived from the so-called Syno1 process (B. H. Weil and J. C. Lane, "Synthetic Petroleum from the Synthine Process, Chemical Publishing Co., 1948, pages 154 and-273). The Synol process is a modied HCS process employing a highly active iron catalyst, a. typical catalyst comprising iron, 3.5% alumina based on the weight of iron and 0.15 to 0.5% of KzO. A water gas charging stock is converted in the presence of this type of catalyst to straight chain terminal alcohols having molecular weights as high as C20 and to olenic hydrocarbons. The concentration of alcohol and olefins in the Syno1 product may reach 70 to in which as much as 60% may be alcohols, together with small proportions of esters, aldehydes and ketones. Operations are usually effected at 180 to 200 C. and 18 to 30 atmospheres, employing 2,000 to 3,000 volumes per hour of water gas per volume of catalyst in recycle fixed bed operation. The application of the selective extraction process of the present invention to Syno1 process reaction products makes possible the segregation of oxygenated compounds, particularly the alcohols on the one hand, and olens, on the other hand. This type of separation is very dlilicult to achieve by the employment of solvents other than the amine sulfonates, because conventional solvents extract both olens and oxygenated compounds and, furthermore, acidic solvents such as phosphoric acid and sulfuric acid enter into reaction with the olefins causing the formation of alkyl sulfates and/or olefin polymers.

The selective extraction process of the present invention may also be applied to hydrocarbon oil fractions containing neutral, oxygenated organic compounds derived by thermal or catalytic oxidation of hydrocarbon charging stocks such as naphtha, kerosene, gas oil and other hydrocarbon oil fractions. These processes are well known and some are in actual operation. The separation of neutral, oxygenated organic compounds from fractions produced by the oxidation of hydrocarbons presents a difficult problem to which considerable research has been addressed (noteA for example J. A. Camelford, U. S. Patent 2,348,191, patented May 9, 1944).

Reference is made tothe following examples, which are intended to illustrate, but not necessarily to limit, the process of the present invention.

EXAMPLE 1 A mixture of isomeric nonyl alcohols was prepared by subjecting an isobutylene-n-butylene codimer to the OXO process, i. e. to treatment in the liquid phase witha cobalt catalyst and an equimolar mixture of carbon monoxide and hydrogen at a temperature of about C. and a pressure of about 3000 p. s. l., followed by treatment of the intermediate Ca aldehyde product with hydrogen in the presence of a cobalt hydrogenation catalyst at a temperature of about 250 C. and a pressure of about 800 p. s. i. g. A mixture was prepared containing 0.5 volume off the isomerlc nonyl alcohols thus prepared and 0.5 volume of n-dodecane. This mixture was mechanically agitated with an equal volume of the triethylamine salt of a mixture of (3i-C4 alkanesulfonic acids at C. for a period of 15 minutes, following which agitation was discontinued and the mixture allowed to separate by gravity into a lower extract layer and a supernatant raiilnate layer. The two liquid layers were separated by decantation and the extract layer was then diluted with about an equal volume of water at room temperature, following which the aqueous extract was subjected to steam distillation. The extract amounted to 1.60 volumes and the raftinate or hydrocarbon phase to 0.40 volume. The following data were obtained.

TABLE IV Extraction of nonyl alcohols-n-dodecane mixture with triethylamine alkanesulfonates Volume percent Percent Alcohol Percent of alcohol extracted from soln.=84. Percent oi dodecanc extracted from 50% soln.=28.

EXAMPLE II TABLE V Extraction of diethyl ketone-n-heptane mixture with triethyla'rmine ethanesulfonate Volume Percent "D20 dm percent Ketone Diethyl Ketone 1. 3948 0. 814 n-Heptane 1. 3882 0. 682 50/50 Feed Mixture l. 3901 0. 748 100 50 Rainate 1. 3886 0. 727 73 34 Extract 1. 3933 0. 798 27 89 Percent oi ketone extracted from 50% so1n.=45.0. Percent of heptane extracted from 50% soln.=8.0.

EXAMPLE3 An HCS operation was effected by treating ian equimolar mixture of carbon monoxide and hydrogen with an alkalized iron catalyst at 600- 660 F. and 250 p. s. i. g. and the hydrocarbon product was washed with alkali and then fractionated to separate a fraction boiling in the range of 126 to 151v C. consisting essentially of hydrocarbons containing, on the average, 9 carbon atoms per molecule and neutral, oxygen-'ated organic compounds containing, on the average,

7 carbon atoms per molecule. 'I'hls fraction contained 40 to 50 weight percent of olens and 15 to 20 weight percent of neutral, oxygenated organic compounds, compriisng Iprincipally alcohols and carbonyl compounds. One volume of said HCS liquid hydrocarbon fraction was mechanically agitated at 25 C. for 15 minutes with one volume of the triethylamine salt of a mixture of C1-C4 alkanesulfonic acids, following which the mixture was allowed to separate by gravity into extract and raffinate layers. The extract layer amounted to 1.16 volumes and the hydrocarbon or raillnate layer amounted to 0.84 volume. The liquid layers were separated by decantation and the solute in the extract layer was recovered by dilution with about an equal weight of water followed by steam distillation and separation of distilled oxygenated compounds by condensation and settling from water passing overhead from the steam still. Ultimate analyses were made of the charging stock, the` extract and the raffinate layers, the results being given in the following table. On the basis of this data, 62.5 weight percent of the oxygen compounds in the charging stock were extracted from the HCS liquid fractions, which originally contained 11.1 weight percent of neutral, oxygenated organic compounds. The concentration of oxygenated compounds in the extract layer was 40.2 weight percent and in the railinate layer was 4.8 weight percent.

TABLE VI Analyses and Material Balance for Process Charge-75.63 g. Estimate-63.03 g. Extract-12.67 g.

Weight. Weight, Weight, Weight, Weight, Weight, Percent g. Percent g. Percent g.

Carbon.-- 84. 64. 15 85. 65 53. 96 81.48 l0.,33 Hydrogen. 13. 65 10. 32 13. 89 8. 75 l2, 82 1. 64 Oxygen.-- l. 54 1. 16 O. 67 0. 42 5. 55 0. 70

Total..- 100.04 75. 63 100. 21 63. 03 '99. 85 12.67

(1) 75.63 g. material charged-75.70 g. material recovered. (2) 64.15 g. carbon charged-64.29 g. carbon recovered. (3) 10.32 g. hydrogen charged-10.39 g. hydrogen recovered. (4) 1.16 g. oxygen charged-1.12 g. oxygen recovered.

An illustrative process flow and suitable operating equipment are schematically depicted in Figure 2, from which various valves, pumps, heat exchangers, etc. have been eliminated in the interests of simplicity. Referring now to Figure 2, a charging stock for example an HCS liquid fraction boiling in the gasoline or naphtha range and containing carboxylic acids as well as neutral, oxygenated organic compounds, monoolenic hydrocarbons, paraninic hydrocarbons and small proportions of aromatic hydrocarbons, is passed through valved line I0 into the lower portion of a washing tower il wherein it flows countercurrently to a stream of water introduced by line I2 into the upper portion of tower Il. The tower may be provided with suitable packing or spacing materialsas is conventional in the liquidliquid extraction art. The water extraction operation may be conducted at room temperature or slightly elevated temperatures up to about 75 C.. in order to remove preferentially Water-soluble oxygenated compounds from the charging stock. The aqueous extract is removed from tower Il through line i3, whence all or a portion thereof may be recycled to line I2 for reuse as the absorption medium. Alternatively, part of all of the aqueous extract may be treated, for example by distillation. solvent extraction, etc.,

to separate the solute from the aqueous extract phase.

The water-washed charging stock passes overhead from tower II through line II, thence through a heat exchanger I5, to provide suitable temperature adjustment, in the lower portion of washing tower I6, in which it ows countercurrently to an aqueous alkali stream introduced by line I'I into the upper portion of tower I6. Tower I 6 may be provided with suitable spacing or packing materials, as is well known in the art. We may employ various alkalies dissolved or dispersed in wrater or other solvents or carrying media, e. g., methanol or ethanol. Suitable alkalies comprise NaOH, NaHCOs, NazCOa, the corresponding potassium-based alkalies, etc. The alkali washing may be effected lat ambient temperatures, e. g., between about 10 and about 50 C. The purpose of the alkali extraction operation is to remove acidic constituents, particularly carbooxylic acids, which may be contained in the charging stock. The Ialkaline extract phase is withdrawn from tower I6 through line I8,

whence all or a portion may be recycled to the upper end of tower I6. Preferably, however, at least an 'aliquot portion of the alkaline extract is treated to liberate the solute contained therein, for example by acidification with dilute mineral acids such as sulfuric acid, followed by steam distillation.

It shoufld be remarked that the alkali extraction operation Iwhich is effected in tower I6 results in the production of alkali metal carboxylates which solutize normally insoluble alcohols and carbonyl compounds in the aqueous lallkali, thereby reducing noto-nly the carboxylic acid content of the feed stock passing into tower I6, but also reducing the concentration of alcohols and carbonyl compounds in the feed stock.

The alkali-treated feed stock passes overhead from tower I 6 through line I9, thence through heat exchanger 2|] wherein its temperature is suitably adjusted, into contacting zone 2I If desired, this alkali-treated feed stock may be waterwashed and dried before passing to heat exchanger '20l Zone 2I may take the form of conventionall contacting equipment such as has heretofore been employed in effecting selective solvent extraction of lubricating oils, illuminating oils, etc., or in the processes for the extractive distillation of hydrocarbon oils. The contacting equipment may comprise a vertical tower,. which is preferably provided with packing or spacing materiafls to insure thorough contacting of the hydrocarbon feed stock and the amine sulfonate solvent. Suitable materials of construction for the contacting zone are aluminum and stainless steel, which have proven strongly resistant to corrosion by alkyl ammonium sulfcnates, although it should be understood that `we may employ other construction materials, for example glass-, ceramicor carbon-lined iron towers. Suitable spacing materials comprise shaped fragments, for example Berl saddles or Raschig rings made of carbon, porcelain, glass, aluminum, stainless steel, etc.; stainless steel jack chain: stainless steel or aluminum screens which may be shaped, for example, in the form of Scofield, McMahon or Stedman packing, etc. If desired, the contacting tower may be jacketed or provided with heat exchange coils to permit maintenance of the desired temperature.

In a desirable method of operation, the feed stock is passed into the ilower portion of zone ZI against a counterflow of an amine sulfc-nate, f-or example, triethylammonium ethanesulfonate, which is introduced` into the upper portionof tower 2| through lines 22 and 23. Diluents, e. g. pentane or hexane, or modifying solvents, e. g., methanol, may be introduced with the `feed stock, the amine sulfonate solvent or separately, through a line not shown, into zone 2 I.

'Ilhe contactingof the amine sulfonate `and charging stock resu-'lts in the production of railinate and extract phases whose common boundary or interface is indicated at 24. The countercurrent extraction zone may be operated with either the charging stock o-r solvent Ias the continuous phase. In the mode of operation illustrated in Figure 2 the extract phase is shown as the continuous phase, through which the hydrocarbon feed stock is introduced as the dispersed phase.

The rainate phase forms a supernatant layer l above interface 24 in zone 2I, whence it is discharged through line 25. The railinate phase contains a substantially reduced content of neutral, oxygenated organic compounds, as well as any aromatic hydrocarbons or sulfur compounds contained in the feed stock, as compared with the feed stock. It should be understood, however. that the raflnate phase may be further treated to reduce its content of neutral, oxygenated organic compounds, sulfur compounds and aromatic hydrocarbons, if it is so. desired. For this purpose, a portion at least of the railinate phase may be recycled from line 25 by a line not shown to re-enter rlone 2I with fresh feed stock. Alternatively, or in addition, the rafhnate in line 25 may be sent to another contacting zone, identica-l in all substantial respects with zone 2l, for treatment in a second stage with fresh solvent, which may be the same amine sulfonate or a different amine sulfonate from that passing into line 22, or may be an entirely different type of solvent, e. g., liquid hydrogen fluoride, HF-BFa, liquid SO2, phenol, furfural, this-(beta-chloroethyl) ether, etc. It should be noted that further extraction of the raffinate passing through line 25 with solvents different from the amine sulfonate passing through line 22 is greatly facilitated by the fact that the amine sulfonate is substantially insoluble in said rainate, averting the necessity of special procedures for the removal of said amine sulfon-ate from said raflinate. The in- -appreciable solubility of the amine sulfonate of this invention in the raffinate phases is noteworthy and substantially different from the behavior heretofore observed in extraction processes employing conventional solvents, such as phenol, furfural, nitromethane, etc.

The extract phase is withdrawn from the lower end of tower 2I thro-ugh line 26, Vwhence it is passed into separation zone 2l. If desired, a part of the extract in line 26 may be recycled to feed line 23 by means of a line not shown in the drawing. Zone -21 may be a separating vessel into which water or aqueous solvents are introduced by line 28 in suitable amounts, e. g., between about 0.5 and about 3.0 volumes per volume of extract, to effect the resolution of the extract into an aqueous amine sulfonate layer and a layer comprising essentially neutral, oxygenated organic-compounds. Alternatively, the separation zone 21 may take the form of a distillation vessel, preferably a steam distillation vessel, in which the neutral, oxygenated organic compounds are Vaporized, with steam introduced through line 28, and pass overhead through line 29 and heat exchanger 30 into a settling vessel 3|, whence the water layer i5 Withdrawn through valved line 32 hot inert gases such as flue gas, nitrogen, carbon dioxide or other inert gases to eiect substantial dehydration thereof, following which the treated amine sulfonate may .be recycled to extraction zone 2l. Alternatively, the recycle stream of amine sulfonate may be dehydrated by azeotropic distillation of wate'r therefrom with various azeotroping agents, e. g., benzene, toluene, n-heptane, etc. At least partial dehydration of the recycled solvent is necessary when the extract is sprung 'by means of water or Wet steam.

Although Figure 2 represents a continuous countercurrent, single stage extraction operation, it will be apparent that the process of the present invention is amenable to batch processing, multi-stage operation, concurrent flow of solvent and feed stock, the use of knot-hole or other mechanical mixers for feed and solvent in series with one or more settling zones and other variations that will no doubt occur to those skilled in the art without departing from the spirit of this invention.

Having thus described our invention, what we claim is:

l. A process for the selective extraction of a neutral, oxygenated organic compound from a solution thereof in a hydrocarbon mixture comprising essentially an aliphatic hydrocarbon, which process comprises contacting said solution with a selective solvent consisting essentially of an amine salt of a sulfonic acid, said salt having the formula where R1 and R2 are selected from the class consisting of hydrogen and saturated hydrocarbon radicals, R3 is a saturated hydrocarbon radical, and R4 is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals, said amine salt containing between 4 and 20 carbon atoms, inclusive, per molecule, and separating an extract phase comprising said selective solvent and said neutral, oxygenated organic compound.

2. The process of claim l wherein the amine sulfonate contains between 5 and 12 carbon atoms, inclusive, per molecule.

3. The process of claim 1 wherein the hydrocarbon mixture comprises essentially a mono-oleflnic hydrocarbon.

4. The process of claim 1 wherein said solution comprises essentially neutral, oxygenated organic l2 compounds and mono-oleiinic hydrocarbons produced by the hydrogenation of carbon monoxide in the presence of a catalyst comprising essentially iron.

5. The process of claim 4 wherein the hydrocarbon fraction boils within the boiling range of gasoline.

6. A process for the selective extraction of a neutral, oxygenated organic compound from a. solution thereof in a hydrocarbon mixture comprising essentially an aliphatic. hydrocarbon, which process comprises contacting 'said solution with between about 0.1 and about 10 volumes, per volume of said solution, of a selective solvent consisting essentially of an amine salt having the formula R1 Rrtmsoln Ra v wherein R1 and Rz are selected from the class consisting of hydrogen and saturated hydrocarbon radicals, R3 is a saturated hydrocarbon radical, and R4 is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals, said amine salt containing between 4 and 20 carbon atoms, inclusive, per

molecule, said contacting being effected at a temperature between about 20 C. and about 180 C. under pressure suflcient to maintain the liquid phase, and separating an extract phase comprising said selective solvent and said neutral, oxygenated organic compound.

7. The process of claim 6 wherein said amine salt contains between 5 and 12 carbon atoms, inclusive, per molecule. l

8. 'I'he process of claim 6 wherein said solution comprises essentially neutral, oxygenated organic compounds and mono-olefinic hydrocarbons produced by the hydrogenation of carbon monoxide in the presence of a catalyst comprising essentially iron.

9. The process of claim 8 wherein the hydrocarbon fraction boils within the gasoline boiling range.

10. The process of claim 1 wherein R4 is a saturated hydrocarbon radical.

11. The process of claim 1 wherein R4 is an aromatic hydrocarbon radical.

12. The process of claim 1 wherein said selective solvent is a mixture of trethylamine salts of C1-C4 alkanesulfonic acids.

13. The process of claim 1 wherein said selective sohvent is triethylamine ethanesulfonate.

14. The process of claim 6 wherein R4 is a saturated hydrocarbon radical.

ARTHUR A. HARBAN. A CARL E. JOHNSON.

No references cited. 

1. A PROCESS FOR THE SELECTIVE EXTRACTION OF A NEUTRAL, OXYGENATED ORGANIC COMPOUND FROM A SOLUTION THEREOF IN A HYDROCARBON MIXTURE COMPRISING ESSENTIALLY AN ALIPHATIC HYDROCARBON, WHICH PROCESS COMPRISES CONTACTING SAID SOLUTION WITH A SELECTIVE SOLVENT CONSISTING ESSENTIALLY OF AN AMINE SALT OF A SULFONIC ACID, SAID SALT HAVING THE FORMULA. 